A substantial amount of arc welding is now done industrially by the use of robotic and automatic welding equipment wherein a supply of welding wire is pulled from a drum by a wire feeder and pushed through a welding cable and then through a welding gun movable along a workpiece. The robot performs a continuous welding operation. The welding torch includes a tubular contact tip allowing a welding current to be conducted to the wire moving through a wire receiving passage in the contact tip so the current between the wire and workpiece melts the wire for deposition of the metal onto the workpiece. This robotic or automatic type welding equipment operates continuously over many hours repeating the same welding operation. Thus, it is essential that the moving welding wire be provided to the welding operation while advancing at the desired rate coordinated with the controlled rate of movement between the electrode or wire and the workpiece. Accordingly, smooth, controlled feeding of electrode wire into the welding torch is an essential part of the welding operation.
Existing designs of Flux Cored Self Shielded (FCAW-S) semi-automatic guns use a reverse bend in the gun tube (nozzle assembly) to increase pressure at the contact tip. The reverse bend is typically placed within the last three inches of the nozzle assembly behind the contact tip and is in addition to a bend of 0 to 90 degrees in a gooseneck position placed farther away from the contact tip behind the reverse bend. An increase in pressure between the electrode and contact tip will typically produce a more consistent arc in some cases. However, increasing pressure between the electrode and the contact tip also creates more drag on the electrode as it is fed through the gun. This is usually not a problem and can be a benefit to some of the stiffer, larger diameter FCAW-S electrodes. As FCAW-S electrodes have evolved, however, the diameters have become smaller and the sheaths (i.e., metal jackets) have become thinner. This results in the electrode losing rigidity and becoming more susceptible to feeding problems. Common feeding problems include slipping at the drive rolls that feed the electrode or buckling of the electrode after it leaves the drive rolls. A reverse bend near the contact tip can also make feeding of a smaller and less rigid electrode more difficult due to bending or kinking of the electrode wire as it is fed through the bend.
Thus, it is considered desirable to provide a nozzle assembly for a welding torch without a reverse bend to overcome the above-mentioned deficiencies and others while providing better, more advantageous results.